1. Field of the Disclosure
This invention relates to electroluminescent benzofluorenes. It also relates to electronic devices in which the active layer includes such a benzofluorene composition.
2. Description of the Related Art
Organic electronic devices that emit light, such as light-emitting diodes that make up displays, are present in many different kinds of electronic equipment. In all such devices, an organic active layer is sandwiched between two electrical contact layers. At least one of the electrical contact layers is light-transmitting so that light can pass through the electrical contact layer. The organic active layer emits light through the light-transmitting electrical contact layer upon application of electricity across the electrical contact layers.
It is well known to use organic electroluminescent compounds as the active component in light-emitting diodes. Simple organic molecules such as anthracene, thiadiazole derivatives, and coumarin derivatives are known to show electroluminescence. Semiconductive conjugated polymers have also been used as electroluminescent components, as has been disclosed in, for example, U.S. Pat. Nos. 5,247,190, 5,408,109, and Published European Patent Application 443 861.
However, there is a continuing need for electroluminescent compounds, especially compounds that are blue-emitting.